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Re: number problem [message #61282 is a reply to message #61232]

Sat, 12 July 2008 14:58

Jeremy Bailin
Messages: 618
Registered: April 2008

Senior Member

On Jul 10, 3:17 pm, "R.G. Stockwell" <notha...@noemail.com> wrote:
> <pgri...@gmail.com> wrote in message
>
> news:c8f5bb5a-7b15-4abd-bf13-1587add65abe@j22g2000hsf.google groups.com...
>
>
>
>> R.G. Stockwell wrote:
>>> <d.po...@gmail.com> wrote in message
>>> news:43fbf367-1b18-473e-a047-3ce39612f806@x35g2000hsb.google groups.com...
>>> .... snipped ...
>
>>>> yes that was the problem!!1
>>>> it is works properly.but for lat-lon data as you can see it is not:
>>>> 499690.96 3387795.6
>
>>>> i need more details like this
>>>> 499690.95879779 3387795.57157002
>
>>> WHOA WHOA WHOA WHOA!!
>
>>> While we are being pleasant and thinking about what we are doing,
>>> let's think about what it means when you say you need 8 digits of
>>> lat and lon. (hint, think in millimeters)
>
>>> Granted this is somewhat beside the point of how to read data, but if
>>> anyone
>>> ever reviews a lat or a lon with more than 2 decimal points, they will
>>> flag
>>> it.
>
>> On the other hand, google maps will pinpoint
>> the location of my office at
>
>> 42.381009N, 71.128014W
>
>> whereas that would be a bit off if it only
>> had 2 decimals... ;-)
>
>> Ciao,
>> Paolo
>
> True, 2 decimals places is about 1km (roughly). But 71.128014W
> implies a precision of about 10 cm. That is smaller than the window.
> Geophysical data - that is large enough to use lat and lon, is quite
> often not taken on a resolution of cms.
>
> Incidentally, three decimal places works just fine.
> 42.381N, 71.128W (100 m resolution)
>
> I used latitude with minutes and seconds in my phd defense, noting the
> position of
> an instrument. The examiner called me on it. Luckily I had used
> extremely detailed plots of the land to determine the lat and lon,
> and it did have an accuracy down to 10 meters. :)
>
> Cheers,
> bob

Well, that's an accuracy of 36 microarcsec. If those were sky
coordinates (ie. RA, dec) instead of lat, long, that's perfectly
reasonable in certain circumstances (eg. GAIA is supposed to give
better astrometry than that).

-Jeremy.

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[Message index]

		number problem By: d.poreh on Wed, 09 July 2008 03:50
		Re: number problem By: pgrigis on Thu, 10 July 2008 13:14
		Re: number problem By: R.G. Stockwell on Thu, 10 July 2008 12:17
		Re: number problem By: Jeremy Bailin on Sat, 12 July 2008 14:58
		Re: number problem By: pgrigis on Thu, 10 July 2008 10:25
		Re: number problem By: R.G. Stockwell on Thu, 10 July 2008 09:51
		Re: number problem By: d.poreh on Thu, 10 July 2008 08:20
		Re: number problem By: Paul Van Delst[1] on Thu, 10 July 2008 08:17
		Re: number problem By: Paul Van Delst[1] on Thu, 10 July 2008 08:12
		Re: number problem By: David Fanning on Thu, 10 July 2008 08:07
		Re: number problem By: d.poreh on Thu, 10 July 2008 08:04
		Re: number problem By: David Fanning on Thu, 10 July 2008 07:57
		Re: number problem By: Spon on Thu, 10 July 2008 07:50
		Re: number problem By: Vince Hradil on Thu, 10 July 2008 07:38
		Re: number problem By: David Fanning on Thu, 10 July 2008 07:22
		Re: number problem By: Paul Van Delst[1] on Thu, 10 July 2008 07:18
		Re: number problem By: d.poreh on Thu, 10 July 2008 07:14

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